(19)
(11) EP 1 178 497 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
05.02.2003 Bulletin 2003/06

(43) Date of publication A2:
06.02.2002 Bulletin 2002/06

(21) Application number: 01306528.9

(22) Date of filing: 31.07.2001
(51) International Patent Classification (IPC)7: H01F 1/055, H01F 41/02
(84) Designated Contracting States:
AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE TR
Designated Extension States:
AL LT LV MK RO SI

(30) Priority: 31.07.2000 JP 2000231244
31.07.2000 JP 2000231248

(71) Applicant: SHIN-ETSU CHEMICAL CO., LTD.
Chiyoda-ku Tokyo (JP)

(72) Inventors:
  • Sakaki, Kazuaki c/o Magnetic Materials Res. Center
    Takefu-shi, Fukui-ken (JP)
  • Shimao, Masanobu c/o Magnetic Materials Res. Ce.
    Takefu-shi, Fukui-ken (JP)
  • Nakamura, Hajime, c/o Magnetic Materials Res. Ce.
    Takefu-shi, Fukui-ken (JP)
  • Minowa, Takehisa, c/o Magnetic Materials Res. Ce.
    Takefu-shi, Fukui-ken (JP)

(74) Representative: Stoner, Gerard Patrick et al
MEWBURN ELLIS York House 23 Kingsway
London WC2B 6HP
London WC2B 6HP (GB)

   


(54) Sintered rare earth magnets and methods of preparation therefor


(57) A sintered rare earth magnet consisting essentially of 20-30% by weight of R (wherein R is Sm or a mixture of Sm and another rare earth element), 10-45% by weight of Fe, 1-10% by weight of Cu, 0.5-5% by weight of Zr, and the balance of Co has on its surface a composite layer containing Sm2O3 and/or CoFe2O4 in Co or Co and Fe. The magnet is resistant to hydrogen embrittlement.





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